Dry vacuum-pump.



E. W. CHRISTIE.

DRY VACUUM PUMP.

APPLICATION FILED 33.16, 1912.

1,093,313. Patented Apr. '14, 1914.

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M'hwssas Inventor, 6W0 Wm m his fliiarlzqgs COLUMBIA PLANDGRAPH Co,WAsmNG'roN, D. c.

E. W. CHRISTIE.

I DRY VACUUM PUMP. APPLICATION FILED PEB.16, 1912.

Patented Apr. 14, 1914.

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COLUMBIA PLANouRAPH COWWASHINUTON. D.c.

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DRY VACUUM PUMP. APPLICATION FILED FEB.16,1912.

1,093,231 3; Patented Apr. 14, 1914.

COLUMBIA PLANOGRAPH CO.,WASHIN5TON, D. c.

TINTTED STATES PATENT @FFTQJE.

EVI WILLSON CHRISTIE, 0F SEWAREN, NEW JERSEY, ASSIGNOR TO WHEELER CON-DENSER AND ENGINEERING COMPANY, OF CARTER-ET, NEW JERSEY, A. CORPO-RATION OF NEW JERSEY.

DRY VACUUM-PUMP;

Specification of Letters Patent.

Application filed February 16, 1912.

Patented Apr. 1a, 1914.. Serial No. 678,030.

To all whom it may concern Be it known that I, Evr WILLSON CHRIS- TIE, acitizen of the United States, residing at Sewaren, in the county ofMiddlesex and State of New Jersey, have invented a certain new anduseful Improvement in Dry Vacuum-Pumps, of which the following is aspecification.

My invention relates to vacuum pumps, and particularly to theconstruction of the air cylinders of dry vacuum pumps, wlth the objectof increasing the efliciency of existing structures by the location ofactive elements in the most advantageous position and relation for theperformance of their functions with the greatest economy.

In carrying out my invention, I prov de cylindrical oscillating valvesclosely ad acent to the ends of the air cylinder and at the bottom ofthe same for perfect drainage. These valves are oppositely disposed andare provided for the inlet and discharge of air and they are alsoprovided with a curved intermediate port and these ports in hkepositions simultaneously connect with an intervening fiashport and thecylinder ends, for equalizing the air pressure on opposite faces of theair piston at the moment of reversal of the movement of the air piston,or in other words, connecting the clearance space on the discharge sidewith the opposite end of the cylinder, allowing air present atatmospheric pressure to reexpand into the vacuum on the suction side.This has the further utility'of eliminating the effects of clearance,enabling the pump to draw from the condenser during the entire stroke,all of which is hereinafter more particularly described.

In the drawing, Figure 1 is a vertical longitudinal section through anair cylinder showing the devices of my improvement. Fig. 2 is a centralcross section or vertical section at about the broken lines a m ofFig. 1. Fig. 3 is a vertical longitudinal section similar to F ig. 1,but with the parts in a slightly different position. Fig. 4 is avertical cross section at about the broken lines y y of Fig. 3. -Figs. 5and 6 are vertical longitudinal sections at the lower portion of the aircylinder showing the piston in elevation and in diflerent positions andthe valves in difl'erent positions, and Fig. 7 is a diagrammatic view,illustrating the op eration of the valves in improvement.

Similar letters and numerals of reference indicate similar parts in allthe figures.

a represents the air cylinder, a of the cylinder heads, 6 the air pistonand b the piston rod. The air cylinder is advantageously hollowed, asshown, together with the heads for circulation of a cooling medium, andit is also preferably provided circumferentially with an air intakejacket for the air from the condenser to be drawn into the pump. Theintegral body of the cylinder at the base is provided with two valves 0and a? that are circular in cross section in circular openings adjacentto the respective ends of the air cylinder. The respective ends of theair cylinder are provided with a series of ports 0 al which communicateimmediately with the valves 0 d, as between the location of these valvesand the base of the body, I provide an air intake chamber 6, at its endscommunicating with these valves, also the flashport f, which at its endsalso communicates with the valves and in a parallel plane below theflashport is a discharge port 9, the ends of which dip toward the centerof the valves 0 03. And still again below the discharge port 9 is acentral discharge port 9 these discharge ports 9 and 9 being separatedby the seating of puppet valves 7L and i, which come at opposite sidesof the cylinder and at opposite ends of the discharge ports, and whichvalves permit the air forced past the valves 0 a? and into the dischargeport 9 to press the parts of the puppet discharge valves together andpermit the escape of the air from the port 9 into the port 9 It will benoticed from the drawing, that the valves 0 and (Z are of peculiarshape, that they are provided with a curved upper por tion, with a partin section of T-shape, between which and the upper portion is a curvedport 2. It will also be noticed that these valves are set in oppositionwith their axes parallel and with their axes also extending at rightangles to the line of direction and motion of the piston. It will alsobe apparent from the drawings, that the puppet valves h and z' are onlyin com1nunication with the discharge port 9, the flashport f and the airintake port 6 being closed off therefrom. From Fig. 2, it will also bethe device of my apparent that the air intake port 6 is in communicationall around the cylinder with the opening above the same, which is to beprovided with any suitable cover and connections therefrom to thecondensers well lmown in this art, but forming no part of my invention.

From Fig. 1, it will be noticed that the piston is at the left hand endof the cylinder, having completed its stroke in one direction and readyto move in the opposite direction. At this time, the valves 0 (Z occupythe position illustrated in this Fig. 1, in which their curved ports 2are in communication with the flashport f and the ports 0 (Z at the0pposite ends of the cylinder, consequently the clearance space on thedischarge side is connected with the opposite end of the cylinderallowing air present at atmospheric pressure to reexpand into thevacuum, equalizing the pressure, so as to more readily permit thereverse movement of the piston to be accomplished, or in other words, topermit the piston to start in the opposite direction unhampered by anyvacuum influence.

Fig. 3 illustrates the next following position of the parts, that is, inwhich the piston has made a short movement, and the valve (Z has closed,the valve 0 having partially closed, that is, closed to the opencommunication between the respective ends of the piston that is shown inFig. 1. The position Fig. 1 is only held momentarily, or just longenough to permit of the balancing of the pressure at the two ends of thecylinder and opposite faces of the piston. From the position Fig. 2, thevalves are very quickly shifted so asto bring them into the positionshown in Fig. 5, in which the piston moving to the right draws in theair from the air intake 6 into the left hand end of the air cylinder andat the same time, the piston is forcing the air from the right hand endof the air cylinder through the ports (Z past the valve and into thedischarge port 9, where the pressure causes the puppet valves to openand the air to be discharged from the port 9 into the port From Fig. 4,it will be noticed that both puppet valves are in communication with thesame common and transverse chamber g, consequently both valves act witheach stroke of the piston in opposite directions and the air forcedahead of the piston is quickly discharged. "When the piston reaches theright hand end of the air cylinder, the valves again come substantiallyinto the position shown in Fig. 1, so that momentarily again thepressure at the two ends of the cylinder is the same and the piston isreadily started from the right hand end toward the left hand end inreversing the operation. Fig.

6 shows this position, in which the piston is moving from the righttoward the left hand end of the air cylinder, and in which in theposition of the valve (Z, air from the intake chamber a is being drawnin through the ports (Z into the right hand .end of the air cylinder andthe air from the left hand end is being forced out by the ports 0 aroundthe valve 0 and into the discharge port g and therefrom past bothpuppet. valves orseries of puppet valves into the chamber and so away.The valve 0 oscillates from the position Fig. 6 to the positions Figs. 1and 5, then back to the position Fig. 6, while the valve (Z oscillatesfrom the position Fig. 5

to the positions Figs. 1 and 6 and back, and in this oscillation and asherembefore de piston in each direction, opens up the air V intakechamber a with either end of the air cylinder or opens up the dischargeport g with either end of the air cylinder.

In the diagrammatic view Fig. 7, 3 indicates the fly wheel shaft of thepump, a an oscillating lever centrally pivoted and 5 a connecting rodfrom 3 to 4, and 6 a connecting rod from 4 to cranks upon the ends ofthe valves 0 d. In this figure, the position 1 agrees with the positionof the valves in Fig. 1, the position 2 agrees with the position of thevalves in Fig. 5, and the position 3 agrees with the position of thevalves in Fig. 6, and the parts are so set and timed that the valves aremoved automatically for the performance of their functions in theoperation of the machine.

I claim as my invention:

In a dry vacuum pump, two similar oppositely disposed oscillating valvesplaced adjacent to the opposite ends of the cylinder and stroke andpiston, and each having a curved port therethrough, an interveningflashport, an air intake chamber located above the fiashport, adischarge chamber lo which the puppet valves establish communicationwhen open.

Signed by me this 9th day of February,

EVI 'WILLSON CHRISTIE. lVitnesses J. J. BROWN, W. J. BEST.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

